1. Field of the Invention
The present invention relates to a telescopic actuator that converts a rotation of a rotating shaft of a motor into expansion and contraction movements of an output rod via a planetary reduction gear housed in a first housing and a screw feed mechanism housed in a second housing.
2. Description of the Related Art
An arrangement in which expansion and contraction of an upper link and a lower link of a vehicular suspension system are controlled by a telescopic actuator to thus enhance steering stability performance by suppressing changes in camber angle or contact patch accompanying bumping and rebounding of a wheel, the telescopic actuator being formed from a screw feed mechanism that includes a male thread member and a female thread member that are rotated relative to each other by a motor, is known from Japanese Patent Publication No. 6-47388.
In such a telescopic actuator, the output rod is expanded and contracted by transmitting the rotation of the motor to the screw feed mechanism while reducing the rotation by the planetary reduction gear. In this event, in order to support, with the housing, a thrust force transmitted reversely from the output rod to the male thread member of the screw feed mechanism, it is necessary to hold a thrust-receiving flange, which is provided on the male thread member, in the housing via a thrust bearing. In this regard, it is conceivable that the thrust-receiving flange is held with a locknut that is screwed into an inner peripheral surface of the housing through an opening thereof. However, this approach requires dedicated locking means, such as a circlip, to be provided in order to prevent the locknut from being loosened and then dropping off the housing.